Force Control Module Based on Variable Stiffness Flexible Mechanism

Abstract

The invention provides a force control module based on a variable-rigidity flexible mechanism, and belongs to the technical field of machining. The module comprises a shell, cover plates covering the two ends of the shell, the flexible mechanism, piezoelectric actuators, pre-tightening steel balls and a sensor. The flexible mechanism is arranged between the two cover plates of the shell, the piezoelectric actuators are arranged between the two ends of the flexible mechanism and the cover plates respectively, the pre-tightening steel balls are arranged between the cover plates and the piezoelectric actuators, and the sensor is arranged at the output end of the flexible mechanism. In the contact type operation process, rigidity is actively variable, and contact force exerted on an object and displacement of an executor can be controlled independently. The force control module has high precision and high dynamic reaction performance, and the high-performance execution mechanism can serve as an additional module to provide high-performance actions and direct force control ability to a traditional position control system.

Description

technical field [0001] The invention belongs to the technical field of mechanical processing, in particular to a force control module based on a flexible mechanism with variable stiffness. Background technique [0002] Contact operations that require active power control, such as grinding and deburring, are now possible by using industrialized actuators and additional end modules. Recently many companies (like ABB, Fanuc, Pushcorp, ATI) have integrated force control features into their existing products. ABB and Fanuc use servo motors and gearboxes at each joint to achieve force control of the contact points, and others use additional terminal modules that contain pneumatic actuators to achieve force control. However, these force control operations are all realized through position control, and there are problems such as low precision and sluggish response. [0003] For the force control performance of touch operation, the effective task space inertia plays a very importan...

AI Technical Summary

Problems solved by technology

Although the gearbox solution is effective for most motion control applications, the disadvantage is that the gearbox introduces nonlinear disturbance factors (such as joint friction and joint flexural deformation), and the effective inertia provided by the gearbox is the same as that of the variable speed Proportional to the square root of the ratio, and therefore need to provide a high task space inertia, which results in high impact forces (from free motion to constrained motion), which may cause damage to the workpiece or robot system

But these methods use macrostructures and traditional motors, so these mechanisms are often very bulky, and the rate of change in stiffness is also very slow, because the inertia of the geared motor responsible for adjusting the stiffness is large

These limitations make them unsuitable for interactive force control in contact machining processes, which require bandwidths of 100 Hz or higher

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